Actuator of a parking brake

Abstract

An actuator for a parking brake of a motor vehicle is provided, which includes an electric motor ( 1 ) whose rotor ( 20 has a threaded spindle ( 3 ) on which a spindle nut ( 4 ) is located. Between the threaded spindle ( 3 ) and the spindle nut ( 4 ), rolling bodies are in rolling engagement with threaded paths ( 6, 7 ) formed on the spindle nut ( 4 ) and on the threaded spindle ( 3 ). A cable pull ( 8 ) for actuating a brake acts upon the spindle nut ( 4 ).

1 . Actuator for a parking brake of a motor vehicle, comprising an electric motor ( 1 ), having a rotor ( 2 ) with a threaded spindle ( 3 ), on which a spindle nut ( 4 ) is arranged, wherein between the threaded spindle ( 3 ) and the spindle nut ( 4 ) there are rolling bodies ( 5 ) in rolling engagement with threaded paths ( 6 ,  7 ) formed on the spindle nut ( 4 ) and the threaded spindle ( 3 ), and wherein a cable pull ( 8 ) engages the spindle nut ( 4 ) for activating a brake.  
   
   
       2 . Actuator according to  claim 1 , wherein the threaded spindle ( 3 ) is arranged coaxial to the rotor ( 2 ) and is provided with a second threaded path section of opposite slope, wherein another spindle nut ( 4 ) is arranged on the second threaded path section and wherein another cable pull ( 8 ) engages on the second spindle nut ( 4 ) so that cable pulls are engaged on each of the spindle nuts.  
   
   
       3 . Actuator according to  claim 1 , wherein ball screws ( 9 ) are used, wherein the rolling bodies are formed by balls ( 5   a ), which circulate in endless ball raceways ( 10 ), which are defined by the threaded paths ( 6 ,  7 ) of the threaded spindle ( 3 ) and the spindle nut ( 4 ).  
   
   
       4 . Actuator according to  claim 1 , wherein a locking device ( 11 ) is provided, which prevents rotation of the rotor ( 2 ) and thus the threaded spindle ( 3 ) when no current flows to the electric motor ( 1 ).  
   
   
       5 . Actuator according to  claim 4 , wherein the locking device ( 11 ) has a first locking element ( 12 ) fixed in rotation with the rotor ( 2 ) and a movable second locking element ( 13 ), wherein in a locking position the two locking elements ( 12 ,  13 ) engage each other with a positive fit for preventing rotation of the rotor ( 2 ).  
   
   
       6 . Actuator according to  claim 5 , wherein an electromagnet ( 14 ) fixed to the frame acts on the second locking element ( 13 ), which moves into the locking position through activation of the electromagnet ( 14 ).  
   
   
       7 . Actuator according to  claim 5 , wherein the first locking element ( 12 ) has a toothed disk ( 15 ) fixed in rotation with the rotor ( 2 ) and on whose periphery several teeth ( 16 ) are distributed having gaps ( 17 ) provided therebetween.  
   
   
       8 . Actuator according to  claim 5 , wherein the second locking element has a piston ( 18 ) for engagement with the first locking element ( 12 ).  
   
   
       9 . Actuator according to  claim 8 , wherein a spring force acts on the piston ( 18 ), wherein the piston ( 18 ) is moveable against the spring force into the locking position.  
   
   
       10 . Actuator according to  claim 7 , wherein the piston ( 18 ) engages in one of the gaps ( 17 ) of the toothed disk ( 15 ) in the locking position of the locking device ( 11 ).  
   
   
       11 . Actuator for a parking brake of a motor vehicle, comprising an electric motor ( 1 ), having a rotor ( 2 ) that drives a control element, wherein a locking device ( 11 ) is provided for positive-fit locking of the actuator, and with an emergency unlocking device ( 19 ) for relaxing the locking device ( 11 ) from a load applied for applying the brakes.  
   
   
       12 . Actuator according to  claim 11 , wherein the emergency unlocking device ( 19 ) has a band ( 20 ), which is arranged perpendicular to the rotor axis and which wraps around a contact surface ( 21 ) arranged coaxial to an axis of the rotor.  
   
   
       13 . Actuator according to  claim 12 , wherein the band ( 20 ) is provided with a catch ( 22 ) for active engagement with a counter catch ( 17 ) locked in rotation to the rotor ( 2 ), wherein, in active engagement, the band ( 20 ) prevents rotational movement of the rotor ( 2 ).  
   
   
       14 . Actuator according to  claim 13 , wherein the band ( 20 ) is arranged for movement in a longitudinal direction.  
   
   
       15 . Actuator according to  claim 13 , wherein the rotor ( 2 ) is provided with a toothed disk ( 15 ), having several teeth ( 16 ) distributed over a periphery thereof, the periphery including gaps ( 17 ) formed between the teeth, wherein, in active engagement, the catch ( 22 ) of the band ( 20 ) engages in one of the gaps ( 17 ) forming the counter catch.  
   
   
       16 . Actuator according to  claim 15 , wherein the band ( 20 ) has a pocket ( 24 ), which is defined by a belt ( 23 ) arranged in a longitudinal direction of the band ( 20 ) and by the catch ( 22 ) and in which the teeth ( 16 ) of the toothed disk ( 15 ) engage.  
   
   
       17 . Actuator according to  claim 1 , wherein a housing ( 25 ) of the actuator is provided with a connecting member ( 26 ), on which the spindle nut ( 4 ) is locked in rotation.  
   
   
       18 . Actuator according to  claim 11 , wherein the control element is formed by a ball screw ( 9 ) or other rotary transmission gearing.